Constructed wetlands can be used for reducing nonpoint-source pollution and providing ecological services in a watershed. This paper presents a field monitoring study on water quality improvement in constructed wetlands of five cells in series. The wetland system covers 59.9 ha, or 0.08% of the watershed area; it diverts 7.3 million m 3 (hm 3) water (or 4.3% annual flow) from a degraded river. The results showed that the hydraulic retention times (HRT) of the five cells ranged from 5 to 15 days, 18.4% inflow was lost to seepage and increased evapotranspiration (ET) in the wetlands; the wetlands retained 99.1% total suspended solids (TSS), 60.9% total phosphorus (TP), and 54.4% total nitrogen (TN) from the inflow. Major reductions of TSS and TP were observed in the first two large cells that occupied 57% of the total wetland area. The smaller cells did not show advantages over the bigger ones in pollutant retention as reported in some studies. Although significant water quality benefit can be achieved by the constructed wetlands, the increased water loss may be a concern, particularly in dry regions.

The effects of synthesized silver nanoparticles on electrospun PHBV ultrafine fibers were studied by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA). Addition of silver nanoparticles increased from 0.1% to 2.0%, the sooth ultrafine fiber with an average diameter of about 2 μm formed a non-woven mat was obtained. DSC showed the efficient heterogeneous nucleation by the silver nanoparticles for facilitating PHBV crystallization.The thermal stability of the PHBV/Ag ultrafine fibers improved with the increase in the content of the silver nanoparticles.

Flexible humidity sensors with high sensitivity, fast response time, and outstanding reliability have the potential to revolutionize electronic skin, healthcare, and non-contact sensing. In this study, we employed a straightforward nanocluster deposition technique to fabricate a resistive humidity sensor on a flexible substrate, using molybdenum oxide nanoparticles (MoO x NPs). We systematically evaluated the humidity-sensing behaviors of the MoO x NP film-based sensor and found that it exhibited exceptional sensing capabilities. Specifically, the sensor demonstrated high sensitivity (18.2 near zero humidity), a fast response/recovery time (1.7/2.2 s), and a wide relative humidity (RH) detection range (0−95%). The MoO x NP film, with its closely spaced granular nanostructure and high NP packing density, exhibited insensitivity to mechanical deformation, small hysteresis, good repeatability, and excellent stability. We also observed that the device exhibited distinct sensing kinetics in the range of high and low RH. Specifically, for RH > 43%, the response time showed a linear prolongation with increased RH. This behavior was attributed to two factors: the higher physical adsorption energy of H 2 O molecules and a multilayer physical adsorption process. In terms of applications, our sensor can be easily attached to a mask and has the potential to monitor human respiration owing to its high sensing performance. Additionally, the sensor was capable of dynamically tracking RH changes surrounding human skin, enabling a non-contact sensing capability. More significantly, we tested an integrated sensor array for its ability to detect moisture distribution in the external environment, demonstrating the potential of our sensor for contactless human−machine interaction. We believe that this innovation is particularly valuable during the COVID-19 epidemic, where cross-infection may be averted by the extensive use of contactless sensing. Overall, our findings demonstrate the tremendous potential of MoO x NP-based humidity sensors for a variety of applications, including healthcare, electronic skin, and non-contact sensing.

No abstract